CN105939011A - Optimization method of impedance values of three-winding transformer of substation - Google Patents

Abstract

The invention relates to an optimization method of impedance values of a three-winding transformer of a substation. The method comprises the steps of: (1) setting constraint limit values of short-circuit current of various voltage class sides of the substation and upper and lower limit constraint values of three side impedance percents Uk12%, Uk13% and Uk23% of the transformer; (2) setting short-circuit impedance percent calculation step length segments NUk12%, NUk13% and NUk23% by combining the engineering actual situation to divide calculation point numerical matrixes of the three side impedance percents Uk12%, Uk13% and Uk23%; (3) calculating and judging whether each impedance value meets a manufacturing constraint, a short-circuit current constraint and the like or not on each impedance value calculation point; and (4) taking the maximum single-unit capacity upper limit value, of a reactive power compensation device of the substation, stored in the step (3) as the preferred value. The optimization method has the beneficial effects that a specific and reasonable optimization design of the impedance values of the three-winding transformer is carried out aiming at various substations; the adaptability is high; and the application range is wide.

Description

A kind of optimization method of transformer station three-winding transformer resistance value

Technical field

The present invention relates to transmission & distribution electric field, particularly relate to the optimization side of a kind of transformer station three-winding transformer resistance value Method.

Background technology

The design of short-circuit of power transformer impedance parameter value is the important step in power plant and substation project design.Mesh Before, transformer station's great majority of three electric pressures use three-winding transformer, the selection of three-winding transformer resistance value, directly affect The short circuit current level of three side electric pressures, and the size of capacity of short circuit, the remote-effects low reactive-load compensation equipment of transformer station Single pool-size and group number, closely related with engineering construction economic benefit.

As it is shown in figure 1, be a typical 220kV transformer station (three electric pressures: high-pressure side 220kV, medium voltage side 110kV, low Pressure side 10kV) calculation of short-circuit current schematic diagram.The size of transformer station three side bus short circuit current is all and between different brackets Leakage reactance is closely related, only leakage reactance value x between each electric pressure of reasonable design₁、x₂、x₃, each side electricity could be ensured simultaneously The short circuit current of pressure grade is all within safety range.And x₁、x₂、x₃Size depend on the short-circuit impedance of three-winding transformer Percent value Uk1-2%, Uk1-3%, Uk2-3% (physical relationship is as shown in Equation 1), say, that after system impedance is given, Transformer station three side short circuit current level depend on short-circuit impedance percent value Uk1-2% of three-winding transformer, Uk1-3%, Uk2-3%.

$\begin{array}{c}{x}_1=0.5\×(Uk12\%+Uk13\%-Uk23\%)\×S_j/\left(100S_N\right)\\ x_2=0.5\×(Uk12\%+Uk23\%-Uk13\%)\×S_j/\left(100S_N\right)\\ x_3=0.5\×(Uk13\%+Uk23\%-Uk12\%)\×S_j/\left(100S_N\right)\end{array}---\left(1\right)$

In existing actual engineering design, often use the sufficiently large normal impedance of resistance value or general impedance as design Value, so design can enough meet substation bus bar short circuit current requirement, and redundancy is higher.Change for different regions Power station, its position being in power system is different with status, particularly with the end transformer station that the electrical network degree of coupling is relatively low, owing to being System impedance is of a relatively high, if the general impedance value (normal impedance value) that still employing resistance value is the most too high, it will would make short Road electric current is restricted to extremely low level, and the excessively reduction of low-pressure side capacity of short circuit can bring the electricity that reactive-load compensation equipment switching causes Pressure fluctuation problem: after capacity of short circuit reduces, if single pool-size of reactive-load compensation equipment is relatively big, system electricity when will cause switching Pressure fluctuation is unsatisfactory for quality of power supply requirement, now, by reducing reactive power compensator list pool-size and can only increase reactive-load compensation The group number of equipment makes up the problem of voltage pulsation, and takes this measure will be greatly increased equipment investment and transformer station's occupation of land face Long-pending, thus increase the cost of engineering construction: the most too high the leading to of commonly used resistance value in the current 220kV transformer station of Jiangsu Province Using resistance value transformator, the capacitor of the 6000kvar that the single pool-size of employing simultaneously is less than normal is as reactive-load compensation, and floor space is big, One-time investment cost is high.In sum, reduce substation low-voltage side short circuit current level and improve the list of reactive-load compensation equipment Pool-size is conflicting from principle, mutually restricts.Therefore, how optimized choice transformer impedance (or current limliting electricity is studied Anti-device) impedance design value so that low-pressure side short circuit current level controls within zone of reasonableness, simultaneously improve transformer station idle Single pool-size of compensation equipment, reduces investment outlay, and has the most great meaning.

Currently, with respect to the design of transformer station's three-winding transformer resistance value, major part engineering design all uses warp Test resistance value (general higher resistance value), main transformer (180MVA) the impedance percent generally used such as 220kV transformer station For: Uk12%=13, Uk13%=64, Uk23%=47；Capacity is that the main transformer impedance percent of 240MVA typically takes: Uk1-2%=11, Uk1-3%=34, Uk2-3%=22, and at the series reactance that the low-pressure side anti-rate of construction string is 8%～10% Device limiting short-circuit current.Cause part substation low-voltage side short circuit current level too low；Scheme of Reactive Power Compensation uses quantity simultaneously The equipment that pool-size more, single is less, to solve the too small voltage pulsation problem brought of short circuit current, low in economic efficiency.

At present, domestic three-winding transformer resistance value method for designing is divided into following two type:

1) major part designing institute uses General design scheme (general higher resistance value).This method is taken a part for the whole, no Having universality, the parameter area that General design scheme is given is one group of referential data, and its general impedance value is for major part For transformer station, it is uneconomical, irrational.

2) fraction designing institute the most suitably optimizes, and its method is all to change impedance by artificial repeatedly trial Value also carries out tentative calculation, until finding one group of parameter being more satisfied with.This method has occasionality, and designer may be led to Very few tentative calculation just can find relatively reasonable parameter area, it is also possible to through repeatedly attempting still cannot finding reasonable impedance Value, even and if use the method find relative reasonable value, cannot guarantee that optimization range cover the overall situation.

To sum up, current transformer station's three-winding transformer resistance value design optimization method gear shaper without theoretical supports, artificial calculating is numerous Miscellaneous (needing repeatedly tentative calculation, irregularities), design parameter (being unable to reach optimization, construction cost height, deficiency in economic performance) of poor benefits.

Summary of the invention

Present invention aim to overcome that the deficiency of above prior art, it is provided that a kind of transformer station three-winding transformer resistance value Optimization Design, specifically have techniques below scheme to realize:

The optimization method of described transformer station three-winding transformer resistance value, comprises the steps:

1) constraint limit value and the transformator three side impedance percent of transformer station's each electric pressure side short circuit current are set The bound binding occurrence of Uk12%, Uk13%, Uk23%；

2) short-circuit impedance percent material calculation section N is set according to engineering demand_Uk12%、N_Uk13%、N_Uk23%, and then divide three The calculating point value matrix of side impedance percent Uk12%, Uk13%, Uk23%, calculates point value matrix and a little forms by calculating；

3) calculate calculating on point at each resistance value and judge whether this resistance value meets the constraint and short circuit electricity manufactured Stream constraint, if meeting institute's Prescribed Properties, calculating and preserving this resistance value and calculating Reactive Power Compensation Eqyuipment in Substation corresponding to point Single pool-size higher limit；

4) using step 3) in the maximum of single pool-size higher limit of Reactive Power Compensation Eqyuipment in Substation of preserving as preferably Value, and choose the resistance value of described preferred value corresponding three-winding transformer three side impedance percent as optimum resistance value.

The design further of the optimization method of described transformer station three-winding transformer resistance value is, described step 1) in The bound binding occurrence of transformator three side impedance percent Uk12%, Uk13%, Uk23% represents three-winding transformer three respectively Higher limit that side short-circuit impedance value can be got and lower limit.

The design further of the optimization method of described transformer station three-winding transformer resistance value is, described step 2) in, When dividing the calculating point value matrix of three side impedance percent Uk12%, Uk13%, Uk23%, resistance value is calculated point selection to exist Integral point calculates.

The design further of the optimization method of described transformer station three-winding transformer resistance value is, described step 3) in, According to formula (1) to step 2) in the three-winding transformer impedance of each side percent Uk12%, Uk13%, Uk23% carry out further Limit, the constraint of the manufacturing such as formula (2),

Uk13%-(Uk12%+Uk23%) >=2 (1)

$\begin{array}{c}11\≤Uk12\%\≤15\\ 28\≤Uk13\%\≤79\\ 18\≤Uk23\%\≤65\end{array}.---\left(2\right)$

The design further of the optimization method of described transformer station three-winding transformer resistance value is, described step 3) in, Under maximum operational mode and minimum operational mode, calculate the short-circuit current value of correspondence respectively and judge whether to meet shown in formula (3) Short circuit current constraints,

$\begin{array}{cc}{\stackrel{\‾}{I}}_{Hf3}\≤I_{Hf\max }& {\tilde{I}}_{Hf3}\≤I_{Hf\max }\\ {\stackrel{\‾}{I}}_{Hf1}\≤I_{Hf\max }& {\tilde{I}}_{Hf1}\≤I_{Hf\max }\\ {\stackrel{\‾}{I}}_{Mf3}\≤I_{Mf\max }& {\tilde{I}}_{Mf3}\≤I_{Hf\max }\\ {\stackrel{\‾}{I}}_{Mf1}\≤I_{Mf\max }& {\tilde{I}}_{Mf1}\≤I_{Hf\max }\\ {\stackrel{\‾}{I}}_{Lf3}\≤I_{Lf\max }& {\tilde{I}}_{Lf3}\≤I_{Hf\max }\end{array}---\left(3\right)$

In formula,WithRepresent the high-pressure side three-phase shortcircuit under maximum operational mode and minimum operational mode respectively Current maxima,WithRepresent the medium voltage side three-phase shortcircuit electricity under maximum operational mode and minimum operational mode respectively Stream maximum,WithRepresent the low-pressure side three short circuit current under maximum operational mode and minimum operational mode respectively Maximum.

The design further of the optimization method of described transformer station three-winding transformer resistance value is, described step 3) in, Calculate this resistance value according to formula (4) and calculate Reactive Power Compensation Eqyuipment in Substation list pool-size higher limit Q that point is corresponding_Cmax,

$Q_{Cmax}=0.025S_d=0.025\×\sqrt{3}{U}_{LN}{I}_{Lf3}---\left(4\right)$

Wherein, I_Lf3For low-pressure side three short circuit current under minimum operational mode, U_LNLow-pressure side three-phase voltage, S_dFor low pressure Side capacity of short circuit, Q_CmaxFor capacitor list group heap(ed) capacity.

Advantages of the present invention is as follows:

1) the inventive method can carry out the optimization of concrete reasonably transformer impedance value for various types of transformer stations Change design, strong adaptability, applied range；

2) relative to traditional tentative calculation Optimization Design, the inventive method optimum results can ensure that optimum results is the overall situation Optimum；

3) the three-winding transformer resistance value Optimization Design that the present invention uses, it is accurate and optimum that optimum results ensures, From engineering construction angle, substation project one-time investment cost, remarkable in economical benefits can be greatly saved.

4) according to Practical Project situation, can be hindered by adjustment binding occurrence nargin adaptation three-winding transformer under the conditions of various Anti-value design.

5) present invention is by using MATLAB software for calculation to realize, and calculates speed fast, for routine engineering design, optimizes The calculating time only needs the several seconds.

Accompanying drawing explanation

Fig. 1 is three groups of 8Mvar Capacitor banks arrangement figures.

Fig. 2 is four groups of 6Mvar Capacitor banks arrangement figures.

Detailed description of the invention

Below the present invention program is described in detail.

The first step, sets the constraint limit value of transformer station's each electric pressure side short circuit current.It is limited to switch rupturing capacity requirement, The circuit breaker short circuit finite capacity of the most different electric pressures, therefore, transformer station's each electric pressure side short circuit current should be less than Limit value, shown in its constraint expression formula such as formula (1).

$\begin{array}{cc}{\stackrel{\‾}{I}}_{Hf3}\≤I_{Hf\max }& {\tilde{I}}_{Hf3}\≤I_{Hf\max }\\ {\stackrel{\‾}{I}}_{Hf1}\≤I_{Hf\max }& {\tilde{I}}_{Hf1}\≤I_{Hf\max }\\ {\stackrel{\‾}{I}}_{Mf3}\≤I_{Mf\max }& {\tilde{I}}_{Mf3}\≤I_{Hf\max }\\ {\stackrel{\‾}{I}}_{Mf1}\≤I_{Mf\max }& {\tilde{I}}_{Mf1}\≤I_{Hf\max }\\ {\stackrel{\‾}{I}}_{Lf3}\≤I_{Lf\max }& {\tilde{I}}_{Lf3}\≤I_{Hf\max }\end{array}---\left(1\right)$

In formula,WithRepresent the high-pressure side three-phase shortcircuit under maximum operational mode and minimum operational mode respectively Current maxima,WithRepresent the medium voltage side three-phase shortcircuit electricity under maximum operational mode and minimum operational mode respectively Stream maximum,WithRepresent the low-pressure side three short circuit current under maximum operational mode and minimum operational mode respectively Maximum.At present, due to the constraint of device fabrication level, the short circuit current level constraint of 220kV, 110kV, 10kV electric pressure Value is respectively 50kA, 40kA, 25kA.

Set the constraint limit value of transformer station's each electric pressure side short circuit current and transformator three side impedance percent Uk12%, The bound binding occurrence of Uk13%, Uk23%；

At present, retrained by manufacturing condition, the short-circuit impedance percent of the different electric pressures of high-impedance transformer Given interval can only be arranged on.Tune by domestic Ji Jia transformer manufacturing producer (Siemens, Changzhou Xi electricity Bian Yaqichang) Grinding data, it is considered to transformer production manufacturing condition, three-winding transformer short-circuit impedance percent bound is interval as shown in (2):

$\begin{array}{c}11\≤Uk12\%\≤15\\ 28\≤Uk13\%\≤79\\ 18\≤Uk23\%\≤65\end{array}---\left(2\right)$

Second step, actual according to engineering, set short-circuit impedance percent material calculation section N_Uk12%、N_Uk13%、N_Uk23%, and then Divide the calculating point value matrix of three side impedance percent Uk12%, Uk13%, Uk23%.Actual general with engineering, will resistance Anti-value calculates point selection and calculates in integral point, and the Uk12% numerical value as shown in (2) can choose 11,12,13,14,15, with Reason, Uk12% numerical value can choose 28,29 ..., 78,79, Uk13% numerical value can choose 18,19 ..., 64,65.Uk12%, Uk13%, Uk23% are combined at above data point, form the three-dimensional matrice that corresponding resistance value calculates.Such as, Uk12% =11, Uk13%=28, Uk23%=18, it is simply that one of them resistance value calculates point, shown in (2), have 5 × 52 × 48=12480 calculates point.

3rd step, each resistance value calculate calculate on some judge this resistance value whether meet the manufacturing constraint (as Shown in formula (3)), the constraint such as short circuit current, if meeting institute's Prescribed Properties, calculating and preserving this resistance value and calculating the change that point is corresponding Power station reactive power compensator, such as capacitor, reactor etc., single pool-size higher limit.

As calculated some Uk12%=11, Uk13%=28, Uk23%=18, calculate, due to three-winding transformer Each side impedance percent Uk12%, Uk13%, Uk23% are unsatisfactory for the requirement of formula (3), and therefore this group resistance value is unsatisfactory for constraint Requirement.

Uk13%-(Uk12%+Uk23%) >=2 (3)

As calculated, owing to three-winding transformer is each at calculating point Uk12%=11, Uk13%=34, a Uk23%=22 Side impedance percent Uk12%, Uk13%, Uk23% meet the requirement of formula (3), therefore calculating transformer three side short circuit further Current value, calculates the short-circuit current value of correspondence respectively under maximum operational mode and minimum operational mode, and judges whether to meet Short circuit current constraints shown in formula (1), as met, then calculates this resistance value further according to formula (4) and calculates some correspondence The single pool-size higher limit of Reactive Power Compensation Eqyuipment in Substation (such as capacitor, reactor etc.).

$Q_{Cmax}=0.025S_d=0.025\×\sqrt{3}{U}_{LN}{I}_{Lf3}---\left(4\right)$

Wherein, I_Lf3For low-pressure side three short circuit current under minimum operational mode, U_LNLow-pressure side three-phase voltage, S_dFor low pressure Side capacity of short circuit, Q_CmaxFor capacitor list group heap(ed) capacity；

4th step, screens and each calculates that to meet optimized results in the resistance value of constraints in point (corresponding maximum idle Compensate single pool-size higher limit), and the design load choosing the three-winding transformer three side impedance percent of correspondence sets as engineering Evaluation.

According to aforesaid calculating process, constraint and the short circuit current constraint meeting transformer production manufacturing condition can be filtered out The resistance value of condition calculates the single pool-size upper limit of Reactive Power Compensation Eqyuipment in Substation (such as capacitor, reactor etc.) of point and correspondence Value.Choose transformation corresponding during the single pool-size higher limit of Reactive Power Compensation Eqyuipment in Substation (such as capacitor, reactor etc.) of maximum Device three side resistance value is as final design load.

One specific embodiment of the inventive method given below

Jiangsu 220kV transformer station, year main transformer design scale of going into operation is 1*180MVA capacity, and electric pressure is 220/110/ 10kV, it is to use general impedance value that early stage can grind design: Uk12%=13, Uk13%=64, Uk23%=47, Yao's bridging System impedance value under different running method is as shown in the table.According to local Distribution Network Equipment short circuit current requirement, transformer station is low Pressure side bus short circuit current must not exceed 25kA.

Table 1 is gone into operation system impedance value under year different running method

It is respectively adopted the resistance value after general impedance value scheme and optimization method of the present invention design and carries out Analysis of Short-Circuit Current, And calculating single pool-size of reactive-load compensation equipment, result is as shown in table 2～table 3.

Table 2 main transformer impedance uses general impedance value computation schemes result

Table 3 main transformer impedance uses the resistance value result of calculation after the inventive method optimization

Specifically compare the result of calculation of scheme before and after optimization, it is found that use General design scheme (general impedance value) Time, the short circuit current level of three side electric pressures all can drop to the lowest, now reactive-load compensation equipment (Capacitor banks, reactor) Single pool-size must not be higher than 7.44Mvar, and according to current capacity series, can only use single pool-size is the capacitor of 6Mvar Group, such as Fig. 2；The optimization resistance value using Optimization Design of the present invention to draw, is possible not only to the short circuit of each side electric pressure Levels of current is limited in safety range, reduces the redundancy of capacity of short circuit simultaneously, the reactive-load compensation equipment (electric capacity after optimization Device group, reactor) single pool-size maximum be 9.75Mvar, the Capacitor banks of 8Mvar can be used according to practical situation.

If considering short circuit current constraint nargin further, low-pressure side short circuit current binding occurrence can be reduced to 20kA, using The optimization resistance value that Optimization Design of the present invention draws can be taken as: Uk12%=11, Uk13%=54, Uk23%=41, this Single pool-size maximum of the reactive-load compensation equipment (Capacitor banks, reactor) after Shi Youhua is 8.63Mvar, corresponding maximum Under the method for operation, low-pressure side short circuit current is 21.61kA, and the most still can use single pool-size is the Capacitor banks of 8Mvar, as Fig. 1.

The reactive requirement total capacity of this every main transformer of 220kV transformer station is 24Mvar (capacitive), can grind design if used Scheme (general impedance value scheme), then need 4*6Mvar Capacitor banks scheme, if main transformer resistance value uses the inventive method optimization After resistance value, then can use 3*8Mvar Capacitor banks scheme, after optimization scheme transformer station arrange on can significantly save electricity The floor space in container group place, the capacitor Ground arrangement figure under two kinds of different schemes is as follows.After optimizing, build Scheme can save transformer station's floor space about 75m², transformator is due to the reduction of resistance value, being manufactured into of every transformator simultaneously This also can reduce about 100,000 yuan, and economic benefit is fairly obvious.

Claims (6)

1. the optimization method of transformer station's three-winding transformer resistance value, it is characterised in that comprise the steps:

1) set the constraint limit value of transformer station's each electric pressure side short circuit current and transformator three side impedance percent Uk12%, The bound binding occurrence of Uk13%, Uk23%；

2) short-circuit impedance percent material calculation section N is set according to engineering demand_Uk12%、N_Uk13%、N_Uk23%, and then divide three side resistances The calculating point value matrix of anti-percent Uk12%, Uk13%, Uk23%, calculates point value matrix and a little forms by calculating；

3) calculate calculating on point at each resistance value and judge whether this resistance value meets the constraint manufactured with short circuit current about Bundle, if meeting institute's Prescribed Properties, calculating and preserving this resistance value and calculating single group of Reactive Power Compensation Eqyuipment in Substation corresponding to point Maximum size value；

4) using step 3) in the maximum of single pool-size higher limit of Reactive Power Compensation Eqyuipment in Substation of preserving as preferred value, and Choose described preferred value corresponding three-winding transformer three side impedance percent as optimum impedance percent value.

The optimization method of transformer station the most according to claim 1 three-winding transformer resistance value, it is characterised in that described step Rapid 1) the bound binding occurrence of transformator three side impedance percent Uk12%, Uk13%, Uk23% in represents three winding respectively Higher limit that transformator three side short-circuit impedance value can be got and lower limit, be defined according to formula (1) in actual engineering design,

11≤Uk12%≤15

28≤Uk13%≤79 (1)

18≤Uk23%≤65

The optimization method of transformer station the most according to claim 1 three-winding transformer resistance value, it is characterised in that described step Rapid 2) in, typically by resistance value meter when dividing the calculating point value matrix of three side impedance percent Uk12%, Uk13%, Uk23% Calculate point selection to calculate in integral point.

The optimization method of transformer station the most according to claim 1 three-winding transformer resistance value, it is characterised in that described step Rapid 3) in, the constraint of the manufacturing such as formula (2),

Uk13%-(Uk12%+Uk23%) >=2 (2)

The optimization method of transformer station the most according to claim 1 three-winding transformer resistance value, it is characterised in that described step Rapid 3), in, under maximum operational mode and minimum operational mode, calculate the short-circuit current value of correspondence respectively and judge whether to meet formula (3) the short circuit current constraints shown in,

$\begin{array}{cc}{\stackrel{\‾}{I}}_{Hf3}\≤I_{Hf\max }& {\tilde{I}}_{Hf3}\≤I_{Hf\max }\\ {\stackrel{\‾}{I}}_{Hf1}\≤I_{Hf\max }& {\tilde{I}}_{Hf1}\≤I_{Hf\max }\\ {\stackrel{\‾}{I}}_{Mf3}\≤I_{Mf\max }& {\tilde{I}}_{Mf3}\≤I_{Hf\max }\\ {\stackrel{\‾}{I}}_{Mf1}\≤I_{Mf\max }& {\tilde{I}}_{Mf1}\≤I_{Hf\max }\\ {\stackrel{\‾}{I}}_{Lf3}\≤I_{Lf\max }& {\tilde{I}}_{Lf3}\≤I_{Hf\max }\end{array}---\left(3\right)$

In formula,WithRepresent the high-pressure side three short circuit current under maximum operational mode and minimum operational mode respectively Maximum,WithRepresent that the medium voltage side three short circuit current under maximum operational mode and minimum operational mode is the most respectively Big value,WithRepresent that the low-pressure side three short circuit current under maximum operational mode and minimum operational mode is maximum respectively Value.

The optimization method of transformer station the most according to claim 1 three-winding transformer resistance value, it is characterised in that described step Rapid 3), in, calculate this resistance value according to formula (4) and calculate Reactive Power Compensation Eqyuipment in Substation list pool-size higher limit Q that point is corresponding_Cmax,

$Q_{Cmax}=0.025S_d=0.025\×\sqrt{3}{U}_{LN}{I}_{Lf3}---\left(4\right)$

Wherein, I_Lf3For low-pressure side three short circuit current under minimum operational mode, U_LNLow-pressure side three-phase voltage, S_dShort for low-pressure side Appearance of a street amount, Q_CmaxFor capacitor list group heap(ed) capacity.